X-ray standing waves reveal lack of OH termination at hydroxylated ZnO(0001) surfaces

Abstract

The vertical adsorption distances of the planar conjugated organic molecule 3,4,9,10-perylenetetracarboxylic diimide (PTCDI) on hydroxylated ZnO(0001), determined with the x-ray standing wave technique (XSW), are at variance with adsorption geometries simulated with density functional theory for surface-structure models that consider terminating OH, whereas good agreement is found for PTCDI in direct contact with the topmost Zn layer. The consequential assignment of OH to subsurface sites is supported by additional, independent XSW and energy scanned photoelectron diffraction data and calls for a reconsideration of the prevalent surface models with important implications for the understanding of ZnO(0001) surfaces.

First-principles calculations of hybrid inorganic–organic interfaces: from state-of-the-art to best practice

“…39,101,103,[142][143][144] Like for metal surfaces, these surface modifications can substantially change the interface geometry and chemistry. 145,146 A particular challenge in this context is that adatoms or hydroxyl group are frequently not detectable in (especially LEED or STM) experiments. Rather, their presence can often be inferred only indirectly, e.g., through their impact on the geometry, which requires a combination of theoretical and experimental techniques.…”

Chemical Defects and Energetic Disorder Impact the Energy‐Level Alignment of Functionalized Hexaazatriphenylene Thin Films

“…The formation of these defects leaves unsaturated carbons exposed which can presumably bind to atomic hydrogen and such species are created by the filament of the pressure gauge in the evaporation chamber. [ 42 ] Our pseudo‐isodesmic calculation scheme maintains the saturation of all carbons as shown in Figures S1–S3, Supporting Information. As the lateral ring structures differ for HATCN and HATNA, we also explore the loss of these structures in HAT, which are similar to HATCN, but without peripheric CN groups.…”

Surface modification of ZnO on the Zn-polar 0001 face by self-assembled triptycene-based polar molecules along with an increase of electric conductance

“…The Zn-polar surface, where Zn atoms are set at the topmost layer, is known to be terminated by hydroxyl groups if the face is exposed to the atmosphere. 12,22,[27][28][29][30][31] In our sample preparation procedure, ZnO single crystals are processed in the atmosphere; therefore, it is likely that the surface is terminated by hydroxyl groups. In the SAM, both cyano (−CN) and hydroxyl (−OH) groups of the molecules can face toward the surface by considering the setting on tripod structure of the molecule, whose height shows good agreement with the AFM measurements shown in Fig.…”